Quantum gravity and the large scale structure of the universe

Bertolami, Orfeu; Mourão, José M.; Pérez–Mercader, Juan

doi:10.1016/0370-2693(93)90528-p

Cited by 70 publications

(98 citation statements)

References 33 publications

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“…So one might wonder if actions of the type (15) could be an effective classical description of strong renormalisation effects in the infrared that might appear in GR (see e.g. [34] and references therein), as happens in QCD. In fact, corrections depending on the logarithm of the renormalisation scale are ubiquitous in quantum field theory, and it appears natural to identify the renormalisation scale with a function of the curvature if we want to build an effective classical action for the spacetime metric that takes into account these quantum effects.…”

Section: Discussionmentioning

confidence: 99%

Modified gravity, dark energy and modified Newtonian dynamics

Navarro¹,

Acoleyen²

2006

J. Cosmol. Astropart. Phys.

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We propose a class of actions for the spacetime metric that introduce corrections to the Einstein-Hilbert Lagrangian depending on the logarithm of some curvature scalars. We show that for some choices of these invariants the models are ghost free and modify Newtonian gravity below a characteristic acceleration scale given by a 0 = cµ, where c is the speed of light and µ is a parameter of the model that also determines the late-time Hubble constant: H 0 ∼ µ. In these models, besides the massless spin two graviton, there is a scalar excitation of the spacetime metric whose mass depends on the background curvature. This dependence is such that this scalar, although almost massless in vacuum, becomes massive and effectively decouples when one gets close to any source and we recover an acceptable weak field limit at short distances. There is also a (classical) "running" of Newton's constant with the distance to the sources and gravity is easily enhanced at large distances by a large ratio. We comment on the possibility of building a model with a MOND-like Newtonian limit that could explain the rotation curves of galaxies without introducing Dark Matter using this kind of actions. We also explore briefly the characteristic gravitational phenomenology that these models imply: besides a long distance modification of gravity they also predict deviations from Newton's law at short distances. This short distance scale depends on the local background curvature of spacetime, and we find that for experiments on the Earth surface it is of order ∼ 0.1mm, while this distance would be bigger in space where the local curvature is significantly lower.

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Section: Discussionmentioning

confidence: 99%

Modified gravity, dark energy and modified Newtonian dynamics

Navarro¹,

Acoleyen²

2006

J. Cosmol. Astropart. Phys.

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“…[13,14,16]. Needless to say, with different choices for the RG scale one automatically selects different cosmologies, thus making RG approaches devoid of any firm and generic prediction.…”

Section: Scale-setting Procedure: Importance and Limitationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…Hence, any conclusion about the consistency of cosmological solutions with an arbitrary choice of the RG scale may be quite misleading. Our 1 For interesting work on the scale dependent gravitational coupling see [16].3 scale-setting procedure works well for both flat and curved universes as well as for the matter background with an arbitrary equation of state. We note that if the ordinary energy-momentum…”

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confidence: 98%

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Renormalization-group running cosmologies: A scale-setting procedure

et al. 2005

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For cosmologies including scale dependence of both the cosmological and the gravitational constant, an additional consistency condition dictated by the Bianchi identities emerges, even if the energy-momentum tensor of ordinary matter stays individually conserved. For renormalization-group (RG) approaches it is shown that such a consistency relation ineluctably fixes the RG scale (which may have an explicit as well as an implicit time dependence), provided that the solutions of the RG equation for both quantities are known. Hence, contrary to the procedures employed in the recent literature, we argue that there is no more freedom in identification of the RG scale in terms of the cosmic time in such cosmologies.We carefully set the RG scale for the RG evolution phrased in a quantum gravity framework based on the hypothetical existence of an infrared (IR) fixed point, for the perturbative regime within the same framework, as well as for an evolution within quantum field theory (QFT) in a curved background. In the latter case, the implications of the scale setting for the particle spectrum are also briefly discussed. Recently, indisputable evidence has been mounting to suggest that the expansion of our universe is accelerating owing to the nonvanishing value of unclustered dark energy with negative pressure, see [1]. The crucial evidence for the existence of dark energy [or the cosmological constant (CC)] relies on the CMB observations [2] which strongly support a spatially flat universe as predicted by inflationary models. By combinations of all data a current picture of the universe emerges, in which about 2/3 of the critical energy density of the present universe is made up by a background dark energy with the parameter of the equation of state −1.38 ≤ w ≤ −0.82 at 95% confidence level [3]. Pressed by these data, theorists now need explain not only why the CC is small, but also why dark-energy domination over ordinary matter density has occurred for redshifts z < ∼ 1 (the coincidence problem). Although models with a truly static CC fit these data well, they have two additional drawbacks (besides the coincidence problem): (1) they cannot theoretically explain why the CC is today small but nonvanishing; (2) they have a problem to ensure a phase of inflation, an epoch in the early universe when the CC dominated other forms of energy density. Assessing the possibility to have dynamical dark energy, rolling scalar field models (quintessence fields) [4] with generic attractor properties [5] that make the present dark energy density insensitive to the broad range of unknown initial conditions, have been aimed at dealing with the coincidence problem. Still, a quintessence potential has to be fine-tuned to yield the present ratio of ordinary matter to quintessence energy density, at the same time allowing a phase dominated by matter so that structure can form; therefore these models cannot address the coincidence problem. In addition, such models may have difficulties in achieving the current quintessence equatio...

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“…However, this possibility can not be ruled out. The possibility of General Relativity being modified in the far infrared due to the renormalization group (RG) has been considered in different contexts, for instance, [11,12,13,14]. The previous attempts to apply this picture to galaxies have considered for simplicity point-like galaxies (e.g., [7,8]).…”

Section: Introductionmentioning

confidence: 99%

Elliptical galaxies kinematics within general relativity with renormalization group effects

Rodrigues¹,

Piattella²,

Fabris³

et al. 2013

Proceedings of VIII International Workshop on the Dark Side of the Universe — PoS(DSU 2012)

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We explore the phenomenology of nontrivial quantum effects on low-energy gravity. These effects come from the running of the gravitational coupling parameter G and the cosmological constant Λ in the Einstein-Hilbert action, as induced by the Renormalization Group (RG). The Renormalization Group corrected General Relativity (RGGR model) is used to parametrize these quantum effects, and it is assumed that the dominant dark matter-like effects inside galaxies is due to these nontrivial RG effects. Here we present additional details on the RGGR model application, in particular on the Poisson equation extension that defines the effective potential, also we re-analyse the ordinary elliptical galaxy NGC 4494 using a slightly different model for its baryonic contribution, and explicit solutions are presented for the running of G and Λ. The values of the NGC 4494 parameters as shown here have a better agreement with the general RGGR picture for galaxies, and suggest a larger radial anisotropy than the previously published result.

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Quantum gravity and the large scale structure of the universe

Cited by 70 publications

References 33 publications

Modified gravity, dark energy and modified Newtonian dynamics

Modified gravity, dark energy and modified Newtonian dynamics

Renormalization-group running cosmologies: A scale-setting procedure

Elliptical galaxies kinematics within general relativity with renormalization group effects

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